Arabinofuranosidases

ABSTRACT

The present invention relates to isolated polypeptides having alpha-L-arabinofuranosidase activity and isolated nucleic acid sequences encoding the polypeptides. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the nucleic acid sequences as well as methods for producing and using the polypeptides.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. application Ser.No. 14/680,942 filed Apr. 7, 2015, which is a divisional application ofU.S. application Ser. No. 11/911,683 filed Oct. 16, 2007, which is a 35U.S.C. §371 national application of PCT/DK2006/000213 filed Apr. 25,2006, which claims priority or the benefit under 35 U.S.C. §119 ofDanish application nos. PA 2005 00609 and PA 2005 01562 filed Apr. 26,2005 and Nov. 10, 2005, respectively, and U.S. Provisional ApplicationNos. 60/676,115 and 60/735,661 filed Apr. 29, 2005 and Nov. 10, 2005,respectively, the contents of which are fully incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates to isolated polypeptides havingalpha-L-arabinofuranosidase activity and isolated nucleic acid sequencesencoding the polypeptides. The invention also relates to nucleic acidconstructs, vectors, and host cells comprising the nucleic acidsequences as well as methods for producing and using the polypeptides.

BACKGROUND OF THE INVENTION

Arabinofuranosidases are capable of hydrolyzing terminal non-reducingalpha-L-arabinofuranoside residues in alpha-L-arabinosides and areclassified as EC 3.2.1.55. Arabinofuranosidases have been isolated fromseveral organisms including filamentous fungi. However, very fewalpha-arabinofuranosidases able to liberate arabinose fromdi-substituted xyloses are known. From Bifidobacterium adolescentis anintracellular enzyme able to release arabinose from C3 of di-substitutedxylose (also internally) has been described (Van Laere, 1997, Appl.Microbiol. Biotechnol, 47, 231-235 and Van den Broek, 2005, AppliedMicrobiology and Biotechnology). From barley an enzyme active on mono-and terminally di-substituted xyloses has been isolated, but it haslittle activity on internally di-substituted xyloses (Ferre, 2000, Eur.J. Biochem., 267, 6633-6641). An enzyme from Trichoderma reesei ispossibly active on terminally di-substituted residues (activity seen on3,5-di-O-alpha-Larabinofuranosyl-alpha-L-arabinofuranoside), but has noactivity towards an oligo-substrate with internally C3 substitutedarabinose (Nogawa, 1999, Appl. Environ. Microbiol., 65, 3964-3968).

A comparison with full-length prior-art sequences shows that the matureamino acid sequence shown in SEQ ID NO:2 has 72% homology with an aminoacid sequence from Chaetomium globosum, and the corresponding DNAsequence in SEQ ID NO:1 shows 73% homology with that of thecorresponding Chaetomium globosum DNA sequence. The homology between thesequence shown in SEQ ID NO:2 and the bacterial GH43alpha-L-arabinofuranosidase from Bifidobacterium sp. is 25%. The matureamino acid sequence shown in SEQ ID NO:4 has 38% homology with thearabinofuranosidase from Aspergillus niger.

SUMMARY OF THE INVENTION

The inventors have isolated alpha-L-arabinofuranosidases from strains ofthe filamentous fungi Humicola insolens (SEQ ID NO:2) and Meripilusgiganteus (SEQ ID NO:4). The inventors also isolated the genes encodingthe novel alpha-L-arabinofuranosidases. The enzymes are extracellular.The alpha-L-arabinofuranosidases from Humicola insolens belongs to GH43and the alpha-L-arabinofuranosidases from Meripilus giganteus belongs toGH51.

The alpha-L-arabinofuranosidase from Humicola insolens is able toliberate arabinose from di-substituted xyloses, i.e. thealpha-L-arabinofuranosidase is active on xylose units of wheatarabinoxylan with arabinose attached to C2 and C3. The activity towardsdi-substituted xyloses is essential for total hydrolysis of arabinoxylanto monosaccharides e.g. in production of ethanol from biomass.

Accordingly, in a first aspect the invention provides anarabinofuranosidase derived from a fungus, preferably a species withinHumicola, said arabinofuranosidase capable of releasing arabinose fromdi-substituted xyloses.

Accordingly, in a second aspect the invention provides anarabinofuranosidase which is: a) a polypeptide having an amino acidsequence as the mature peptide shown in SEQ ID NO: 2, or which can beobtained there from by substitution, deletion, and/or insertion of oneor more amino acids; b) an analogue of the polypeptide defined in (i) or(i) which: i) has at least 80% homology with said polypeptide, ii) is anallelic variant of said polypeptide, c) a polypeptide which is encodedby a nucleic acid sequence which hybridizes under high stringencyconditions with a complementary strand of the nucleic acid sequence ofSEQ ID NO:2 encoding the mature polypeptide or a subsequence thereofhaving at least 100 nucleotides.

Accordingly, in a third aspect the invention provides anarabinofuranosidase which is: a) a polypeptide having an amino acidsequence as the mature peptide shown in SEQ ID NO: 4, or which can beobtained there from by substitution, deletion, and/or insertion of oneor more amino acids; b) an analogue of the polypeptide defined in (i) or(ii) which: i) has at least 60% homology with said polypeptide, ii) isan allelic variant of said polypeptide, c) a polypeptide which isencoded by a nucleic acid sequence which hybridizes under highstringency conditions with a complementary strand of the nucleic acidsequence of SEQ ID NO:4 encoding the mature polypeptide or a subsequencethereof having at least 100 nucleotides.

In a fourth aspect the invention provides a nucleic acid sequencecomprising a nucleic acid sequence which encodes the arabinofuranosidaseof the first or second aspect.

In a fifth aspect the invention provides a nucleic acid sequence whichcomprises: a) the DNA sequence encoding any of the arabinofuranosidasesshown in SEQ ID NO:2 and SEQ ID NO:4, b) an analog DNA sequence which i)has at least 80% homology with any of said DNA sequences, or ii)hybridizes at high stringency with a complementary strand of any of saidDNA sequences or a subsequence thereof having at least 100 nucleotides,iii) is an allelic variant thereof, or c) a complementary strand to a)or b).

In a sixth aspect the invention provides a nucleic acid sequence whichhas at least 80% homology with any of the DNA sequences shown in SEQ IDNO:1 and SEQ ID NO:3, or a) hybridizes at high stringency with acomplementary strand of any of said DNA sequences or a subsequencethereof having at least 100 nucleotides, b) is an allelic variantthereof, or c) a complementary strand to a) or b).

In a seventh aspect the invention provides a nucleic acid constructcomprising the nucleic acid sequence of the second, third and fourthaspect operably linked to one or more control sequences capable ofdirecting the expression of the arabinofuranosidase in a suitableexpression host.

In an eighth aspect the invention provides a recombinant expressionvector comprising the nucleic acid construct of the seventh aspect.

In a ninth aspect the invention provides a recombinant host cellcomprising the nucleic acid construct of the sixth aspect.

In a tenth aspect the invention provides a method for producing anarabinofuranosidase comprising cultivating the host cell of the ninthaspect under conditions conducive to production of thearabinofuranosidase, and recovering the arabinofuranosidase.

In an eleventh aspect the invention provides a composition comprisingthe arabinofuranosidase of the first and second aspect.

In further aspects the invention provides uses of thearabinofuranosidases of the first and second aspect.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1A-C show arabinoxylan polymers

FIG. 1A shows intact arabinoxylan.

FIG. 1B shows di-substituted arabinoxylan.

FIG. 1C shows singly substituted arabinoxylan.

FIG. 2 A-C show arabinoxylo-oligosaccharides

FIG. 2A shows arabinosyl groups linked to internal C-3.

FIG. 2B shows arabinosyl groups linked to terminal C-3

FIG. 2C shows arabinosyl groups linked to internal C-2

DETAILED DESCRIPTION OF THE INVENTION

In a embodiment of the second aspect of the present invention, theisolated polypeptide has an amino acid sequence which has at least 80%identity with the amino acid sequence shown as amino acids 1 to 558 ofSEQ ID NO:2. In an interesting embodiment of the invention thepolypeptide has at least 75%, at least 85%, at least 90%, at least 95%,at least 96%, at least 97%, at least 98%, or at least 99% identity withthe amino acid sequence shown as amino acids 1 to 558 of SEQ ID NO:2.

In an embodiment of the third aspect of the present invention, theisolated polypeptide has an amino acid sequence which has at least 50%identity with the amino acid sequence shown as amino acids 1 to 643 ofSEQ ID NO:4. In an interesting embodiment of the invention thepolypeptide has at least 60%, at least 70%, at least 80% at least 85%,at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, orat least 99% identity with the amino acid sequence shown as amino acids1 to 643 of SEQ ID NO:4.

In a preferred embodiment, the isolated polypeptide have an amino acidsequence which differs by five amino acids, e.g. by four amino acids,such as by three amino acids, by two amino acids, or by one amino acidfrom any of the amino acid sequences shown as amino acids 1 to 558 ofSEQ ID NO:2 and 1 to 643 of SEQ ID NO:4.

In an embodiment of the second aspect of the invention, the isolatedpolypeptide is an alpha-L-arabinofuranosidase able to liberate arabinosefrom di-substituted xyloses, e.g. the alpha-L-arabinofuranosidase isactive on xylose units of wheat arabinoxylan with arabinose attached toC2 and C3.

Alignments of sequences and calculation of homology may suitably bedetermined by means of computer programs known in the art such as GAPprovided in the GCG program package (Program Manual for the WisconsinPackage, Version 8, August 1994, Genetics Computer Group, 575 ScienceDrive, Madison, Wis., USA 53711) (Needleman, S. B. and Wunsch, C. D.,(1970), Journal of Molecular Biology, 48, 443-453. The followingsettings for amino acid sequence comparison are used: GAP creationpenalty of 3.0 and GAP extension penalty of 0.1. The relevant part ofthe amino acid sequence for the homology determination is the maturepolypeptide, i.e. without the signal peptide.

Preferably, the polypeptides of the present invention comprise any ofthe amino acid sequences shown as amino acids 1 to 558 of SEQ ID NO:2and 1 to 643 of SEQ ID NO:4, an allelic variant thereof, or a fragmentthereof that has arabinofuranosidase activity. Obviously, thepolypeptide of the invention may also consist of any of the amino acidsequences shown as amino acids 1 to 558 of SEQ ID NO:2 and 1 to 643 ofSEQ ID NO:4.

An allelic variant denotes any of two or more alternative forms of agene occupying the same chromosomal locus. Allelic variation arisesnaturally through mutation, and may result in polymorphism withinpopulations. Gene mutations can be silent (no change in the encodedpolypeptide) or may encode polypeptides having altered amino acidsequences. An allelic variant of a polypeptide is a polypeptide encodedby an allelic variant of a gene.

In an embodiment of the invention, the isolated polypeptide is encodedby a nucleic acid sequence which hybridizes under low stringencyconditions, preferably under medium stringency conditions, morepreferably under high stringency conditions with (i) a complementarystrand of any of the nucleic acid sequences shown as nucleotides 1 to1677 of SEQ ID NO:1 and 46 to 1974 of SEQ ID NO:3, or (ii) a subsequenceof (i) of at least 100 nucleotides (J. Sambrook, E. F. Fritsch, and T.Maniatus, 1989, Molecular Cloning, A Laboratory Manual, 2d edition, ColdSpring Harbor, N.Y.).

The subsequence of the complementary strand of any of the nucleic acidsequences shown as nucleotides 1 to 1677 of SEQ ID NO:1 and 46 to 1974of SEQ ID NO:3, may be at least 100 nucleotides or preferably at least200 nucleotides. Moreover, the subsequence should encode a polypeptidefragment which has arabinofuranosidase activity. The polypeptides mayalso be allelic variants or fragments of the polypeptides that havearabinofuranosidase activity.

The variants of the polypeptides specified comprising a substitution,deletion, and/or insertion of one or more amino acids. In a particularembodiment, the polypeptides are thermostable variants of thepolypeptides specified.

The amino acid sequences of the variant polypeptides may differ from theamino acid sequence specified in amino acids 1 to 558 of SEQ ID NO:2 or1 to 643 of SEQ ID NO:4 by an insertion or deletion of one or more aminoacid residues and/or the substitution of one or more amino acid residuesby different amino acid residues. Preferably, amino acid changes are ofa minor nature, that is conservative amino acid substitutions that donot significantly affect the folding and/or activity of the protein;small deletions, typically of one to about 30 amino acids; small amino-or carboxyl-terminal extensions, such as an amino-terminal methionineresidue; a small linker peptide of up to about 20-25 residues; or asmall extension that facilitates purification by changing net charge oranother function, such as a poly-histidine tract, an antigenic epitopeor a binding domain.

Examples of conservative substitutions are within the group of basicamino acids (arginine, lysine and histidine), acidic amino acids(glutamic acid and aspartic acid), polar amino acids (glutamine andasparagine), hydrophobic amino acids (leucine, isoleucine and valine),aromatic amino acids (phenylalanine, tryptophan and tyrosine), and smallamino acids (glycine, alanine, serine, threonine and methionine). Aminoacid substitutions which do not generally alter the specific activityare known in the art and are described, for example, by H. Neurath andR. L. Hill, 1979, In, The Proteins, Academic Press, New York. The mostcommonly occurring exchanges are Ala/Ser, Val/Ile, Asp/Glu, Thr/Ser,Ala/Gly, Ala/Thr, Ser/Asn, Ala/Val, Ser/Gly, Tyr/Phe, Ala/Pro, Lys/Arg,Asp/Asn, Leu/Ile, Leu/Val, Ala/Glu, and Asp/Gly as well as these inreverse.

The polypeptides referred to herein may comprise the amino acid sequencespecified, or they may be an allelic variant thereof; or a fragmentthereof that has the relevant enzyme activity. In one embodiment, thepolypeptides comprise the amino acid sequence specified or an allelicvariant thereof; or a fragment thereof that has the relevant enzymeactivity. In another embodiment, the polypeptides consist of the aminoacid sequence specified, or an allelic variant thereof; or a fragmentthereof that has the relevant enzyme activity.

A fragment of a specified amino acid sequence is a polypeptide havingone or more amino acids deleted from the amino and/or carboxyl terminusof this amino acid sequence. In one embodiment, a fragment contains atleast 60 amino acid residues, or at least 68, or at least 70, or atleast 75, or at least 100, or at least 150, or at least 160, or at least170, or at least 180, or at least 190, or at least 200, or at least 210,or at least 220, or at least 240, or at least 260, or at least 280, orat least 300, or at least 310, or at least 320, or at least 330, or atleast 334, or at least 350, or at least 375, or at least 400, or atleast 425, or at least 430 amino acid residues.

An allelic variant denotes any of two or more alternative forms of agene occupying the same chromosomal locus. Allelic variation arisesnaturally through mutation, and may result in polymorphism withinpopulations. Gene mutations can be silent (no change in the encodedpolypeptide) or may encode polypeptides having altered amino acidsequences. An allelic variant of a polypeptide is a polypeptide encodedby an allelic variant of a gene.

A mature polypeptide or a mature amino acid sequence refers to that partof an amino acid sequence which remains after a potential signal peptidepart has been cleaved off. And analogously, a mature polypeptideencoding part of a gene refers to that part of a gene, which correspondsto a mature polypeptide.

The nucleic acid sequence of any of SEQ ID NO:1 and SEQ ID NO:3 or asubsequence thereof, as well as the amino acid sequence of any of of SEQID NO:2 and SEQ ID NO:4 or a fragment thereof, may be used to design anucleic acid probe to identify and clone DNA encoding polypeptideshaving arabinofuranosidase activity from strains of different genera orspecies according to methods well known in the art. In particular, suchprobes can be used for hybridization with the genomic or cDNA of thegenus or species of interest, following standard Southern blottingprocedures, in order to identify and isolate the corresponding genetherein. Such probes can be considerably shorter than the entiresequence, but should be at least 15, preferably at least 25, and morepreferably at least 35 nucleotides in length. Longer probes can also beused. Both DNA and RNA probes can be used. The probes are typicallylabeled for detecting the corresponding gene (for example, with ³²P, ³H,³⁵S, biotin, or avidin). Such probes are encompassed by the presentinvention.

Thus, a genomic DNA or cDNA library prepared from such other organismsmay be screened for DNA which hybridizes with the probes described aboveand which encodes a polypeptide having arabinofuranosidase activity.Genomic or other DNA from such other organisms may be separated byagarose or polyacrylamide gel electrophoresis, or other separationtechniques known by the skilled person. DNA from the libraries or theseparated DNA may be transferred to and immobilized on nitrocellulose orother suitable carrier materials. In order to identify a clone or DNAwhich is homologous with SEQ ID NO:1 or SEQ ID NO:3, or a subsequencethereof, the carrier material is used in a Southern blot. For purposesof the present invention, hybridization indicates that the nucleic acidsequence hybridizes to a labeled nucleic acid probe corresponding to anyof the nucleic acid sequences shown in SEQ ID NO:1 and SEQ ID NO:3, itscomplementary strand, or a subsequence thereof, under low to highstringency conditions. Molecules to which the nucleic acid probehybridizes under these conditions are detected using X-ray film.

In another interesting embodiment, the nucleic acid probe is a nucleicacid sequence which encodes any of the (mature) polypeptides of SEQ IDNO:2 and SEQ ID NO:4, or a subsequence thereof. In a third interestingembodiment, the nucleic acid probe is any of SEQ ID NO:1 and SEQ IDNO:3. In a fourth interesting embodiment, the nucleic acid probe is anyof the mature polypeptide coding regions of SEQ ID NO:1 and SEQ ID NO:3.

For long probes of at least 100 nucleotides in length, low to highstringency conditions are defined as prehybridization and hybridizationat 42° C. in 5×SSPE, 0.3% SDS, 200 μg/ml sheared and denatured salmonsperm DNA, and either 25% formamide for low stringency, 35% formamidefor medium stringency, or 50% formamide for high stringency, followingstandard Southern blotting procedures.

For long probes of at least 100 nucleotides in length, the carriermaterial is finally washed three times each for 15 minutes using 2×SSC,0.2% SDS preferably at least at 50° C. (low stringency), more preferablyat least at 55° C. (medium stringency), even more preferably at least at65° C. (high stringency).

For short probes which are about 15 nucleotides to about 70 nucleotidesin length, stringency conditions are defined as prehybridization,hybridization, and washing post-hybridization at 5° C. to 10° C. belowthe calculated T_(m) using the calculation according to Bolton andMcCarthy (1962, Proceedings of the National Academy of Sciences USA48:1390) in 0.9M NaCl, 0.09M Tris-HCl pH 7.6, 6 mM EDTA, 0.5% NP-40,1×Denhardt's solution, 1 mM sodium pyrophosphate, 1 mM sodium monobasicphosphate, 0.1 mM ATP, and 0.2 mg of yeast RNA per ml, followingstandard Southern blotting procedures.

For short probes which are about 15 nucleotides to about 70 nucleotidesin length, the carrier material is washed once in 6×SCC plus 0.1% SDSfor 15 minutes and twice each for 15 minutes using 6×SSC at 5° C. to 10°C. below the calculated T_(m).

As indicated above, the polypeptide of the invention may be apolypeptide having any of the amino acid sequences of SEQ ID NO:2 andSEQ ID NO:4, or the mature polypeptide thereof, wherein one or moreamino acid(s) has (have) been substituted by another (other) aminoacid(s), wherein one or more amino acid(s) has (have) been deleted,and/or wherein one more amino acid(s) has (have) been inserted.

Preferably, amino acid changes are of a minor nature, that isconservative amino acid substitutions that do not significantly affectthe folding and/or activity of the protein; small deletions, typicallyof one to about 30 amino acids; small amino- or carboxyl-terminalextensions, such as an amino-terminal methionine residue; a small linkerpeptide of up to about 20-25 residues; or a small extension thatfacilitates purification by changing net charge or another function,such as a poly-histidine tract, an antigenic epitope or a bindingdomain.

Examples of conservative substitutions are within the group of basicamino acids (arginine, lysine and histidine), acidic amino acids(glutamic acid and aspartic acid), polar amino acids (glutamine andasparagine), hydrophobic amino acids (leucine, isoleucine and valine),aromatic amino acids (phenylalanine, tryptophan and tyrosine), and smallamino acids (glycine, alanine, serine, threonine and methionine). Aminoacid substitutions which do not generally alter the specific activityare known in the art and are described, for example, by H. Neurath andR. L. Hill, 1979, In, The Proteins, Academic Press, New York. The mostcommonly occurring exchanges are Ala/Ser, Val/Ile, Asp/Glu, Thr/Ser,Ala/Gly, Ala/Thr, Ser/Asn, Ala/Val, Ser/Gly, Tyr/Phe, Ala/Pro, Lys/Arg,Asp/Asn, Leu/Ile, Leu/Val, Ala/Glu, and Asp/Gly as well as these inreverse.

In general, it is preferred that the polypeptides of the invention haveat least 20% of the arabinofuranosidase activity of the polypeptidehaving any of the amino acid sequences shown as amino acids 1 to 558 ofSEQ ID NO:2 and amino acids 1 to 643 of SEQ ID NO:4. Particularpreferred are polypeptides, which have at least 30%, such as at least40%, e.g. at least 50%, preferably at least 60%, such as at least 70%,e.g. at least 80%, more preferred at least 90%, or at least 95% of thearabinofuranosidase activity of the polypeptide having any of the aminoacid sequences shown as amino acids 1 to 558 of SEQ ID NO:2 and aminoacids 1 to 643 of SEQ ID NO:4.

A polypeptide of the present invention may be obtained frommicroorganisms of any genus. For purposes of the present invention, theterm “obtained from” as used herein in connection with a given sourceshall mean that the polypeptide encoded by the nucleic acid sequence isproduced by the source or by a cell in which the nucleic acid sequencefrom the source has been inserted. In a preferred embodiment, thepolypeptide is secreted extracellularly.

A polypeptide of the present invention may be a fungal polypeptide, andmore preferably a filamentous fungal polypeptide such as an Acremonium,Aspergillus, Aureobasidium, Cryptococcus, Filibasidium, Fusarium,Humicola, Magnaporthe, Meripilus, Mucor, Myceliophthora, Neocallimastix,Neurospora, Paecilomyces, Penicillium, Piromyces, Schizophyllum,Talaromyces, Thermoascus, Thielavia, Tolypocladium, or Trichodermapolypeptide.

In another preferred embodiment, the polypeptide is an Aspergillusaculeatus, Aspergillus awamori, Aspergillus foetidus, Aspergillusjaponicus, Aspergillus nidulans, Aspergillus niger, Aspergillus oryzae,Fusarium bactridioides, Fusarium cerealis, Fusarium crookwellense,Fusarium culmorum, Fusarium graminearum, Fusarium graminum, Fusariumheterosporum, Fusarium negundi, Fusarium oxysporum, Fusariumreticulatum, Fusarium roseum, Fusarium sambucinum, Fusarium sarcochroum,Fusarium sporotrichioides, Fusarium suiphureum, Fusarium torulosum,Fusarium trichothecioides, Fusarium venenatum, Humicola insolens,Humicola lanuginosa, Meripilus giganteus, Mucor miehei, Myceliophthorathermophila, Neurospora crassa, Penicillium purpurogenum, Trichodermaharzianum, Trichoderma koningii, Trichoderma longibrachiatum,Trichoderma reesei, or Trichoderma viride polypeptide.

In a preferred embodiment of the invention the polypeptide of theinvention is derived from a strain within the Ascomycota, e.g., withinthe genus Humicola, such as within H. lanuginosa H. fuscoatra, H.grisea, H. lutea, H. nigrescens and in particular within H. insolens, orfrom as strain within Basidiomycota, such as within the genus Meripilus,such as within the M. giganteus.

It will be understood that for the aforementioned species, the inventionencompasses both the perfect and imperfect states, and other taxonomicequivalents, e.g., anamorphs, regardless of the species name by whichthey are known. Those skilled in the art will readily recognize theidentity of appropriate equivalents.

Strains of these species are readily accessible to the public in anumber of culture collections, such as the American Type CultureCollection (ATCC), Deutsche Sammlung von Mikroorganismen andZellkulturen GmbH (DSM), Centraalbureau Voor Schimmelcultures (CBS), andAgricultural Research Service Patent Culture Collection, NorthernRegional Research Center (NRRL).

In a particularly preferred embodiment of the invention the polypeptideof the invention is derived from the H. insolens strain described inWO9117243 and deposited Apr. 14 1980 at the German Collection ofMicroorganisms and Cell cultures (DSM, Deutsche Sammlung vonMikroorganismen and Zellkulturen) Göttingen, Germany, under the DSMnumber 1800) in accordance with the provisions of the Budapest Treaty.

In a second particularly preferred embodiment of the invention thepolypeptide of the invention is derived the specific strain of Meripilusgiganteus having the accession number CBS 521.95 in Centraalbureau VoorSchimmelcultures (CBS), Uppsalalaan 8, 3584 CT Utrecht, The Netherlands(alternatively P.O.Box 85167, 3508 AD Utrecht, The Netherlands).

Furthermore, such polypeptides may be identified and obtained from othersources including microorganisms isolated from nature (e.g., soil,composts, water, etc.) using the above-mentioned probes. Techniques forisolating microorganisms from natural habitats are well known in theart. The nucleic acid sequence may then be derived by similarlyscreening a genomic or cDNA library of another microorganism. Once anucleic acid sequence encoding a polypeptide has been detected with theprobe(s), the sequence may be isolated or cloned by utilizing techniqueswhich are known to those of ordinary skill in the art (see, e.g.,Sambrook et al., 1989, supra).

Polypeptides encoded by nucleic acid sequences of the present inventionalso include fused polypeptides or cleavable fusion polypeptides inwhich another polypeptide is fused at the N-terminus or the C-terminusof the polypeptide or fragment thereof. A fused polypeptide is producedby fusing a nucleic acid sequence (or a portion thereof) encodinganother polypeptide to a nucleic acid sequence (or a portion thereof) ofthe present invention. Techniques for producing fusion polypeptides areknown in the art, and include ligating the coding sequences encoding thepolypeptides so that they are in frame and that expression of the fusedpolypeptide is under control of the same promoter(s) and terminator.

Nucleic Acid Sequences

The present invention also relates to isolated nucleic acid sequenceswhich encode a polypeptide of the present invention.

In one interesting embodiment, the nucleic acid sequence has at least80% identity with any of the nucleic acid sequences shown as nucleotides1 to 1677 of SEQ ID NO:1 and 46 to 1974 of SEQ ID NO:2. Preferably, thenucleic acid sequence has at least at least 85%, at least 90%, at least95%, at least 96%, at least 97%, at least 98%, or at least 99% identitywith any of the nucleic acid sequences shown as nucleotides 1 to 1677 ofSEQ ID NO:1 and 46 to 1974 of SEQ ID NO:2. In another interestingembodiment of the invention the nucleic acid sequence comprises any ofthe amino acid sequences shown as nucleotides 1 to 1677 of SEQ ID NO:1,an allelic variant thereof, or a fragment thereof capable of encoding apolypeptide according to the invention. Obviously, the nucleic acidsequence may consist of any of the amino acid sequences shown asnucleotides 1 to 1677 of SEQ ID NO:1 and 46 to 1974 of SEQ ID NO:2.

The present invention also encompasses nucleic acid sequences whichencode a polypeptide having any of the amino acid sequences of SEQ IDNO:2 or SEQ ID NO:4, or the mature polypeptides thereof, which differfrom SEQ ID NO:1 or SEQ ID NO:3 by virtue of the degeneracy of thegenetic code. The present invention also relates to subsequences of SEQID NO:1 or SEQ ID NO:3 which encode fragments of SEQ ID NO:2 or SEQ IDNO:4 that have arabinofuranosidase activity. A subsequence of SEQ IDNO:1 or SEQ ID NO:3 is a nucleic acid sequence encompassed bynucleotides 1 to 1677 of SEQ ID NO:1 or nucleotides 46 to 1974 of SEQ IDNO:3 except that one or more nucleotides from the 5′ and/or 3′ end havebeen deleted.

The present invention also relates to isolated nucleic acid sequencesencoding a polypeptide of the present invention, which hybridize underlow stringency conditions, preferably under medium stringencyconditions, more preferably under high stringency conditions, with (i) acomplementary strand of any of the nucleic acid sequences shown asnucleotides 1 to 1677 of SEQ ID NO:1 and 46 to 1974 SEQ ID NO:3, or (ii)a subsequence of (i) of at least 100 nucleotides. The present inventionalso relates to complementary strands of (i) and (ii).

The techniques used to isolate or clone a nucleic acid sequence encodinga polypeptide are known in the art and include isolation from genomicDNA, preparation from cDNA, or a combination thereof. The cloning of thenucleic acid sequences of the present invention from such genomic DNAcan be effected, e.g., by using the well known polymerase chain reaction(PCR) or antibody screening of expression libraries to detect cloned DNAfragments with shared structural features. See, e.g., Innis et al.,1990, PCR: A Guide to Methods and Application, Academic Press, New York.Other nucleic acid amplification procedures such as ligase chainreaction (LCR), ligated activated transcription (LAT) and nucleic acidsequence-based amplification (NASBA) may be used. The nucleic acidsequence may be cloned from a strain of Humicola insolens or from astrain of Meripilus giganteus, or another or related organism and may,for example, be an allelic or species variant of the polypeptideencoding region of the nucleic acid sequence.

An isolated nucleic acid sequence can, for example, be obtained bystandard cloning procedures used in genetic engineering to relocate thenucleic acid sequence from its natural location to a different sitewhere it will be reproduced. The cloning procedures may involve excisionand isolation of a desired nucleic acid fragment comprising the nucleicacid sequence encoding the polypeptide, insertion of the fragment into avector molecule, and incorporation of the recombinant vector into a hostcell where multiple copies or clones of the nucleic acid sequence willbe replicated. The nucleic acid sequence may be of genomic, cDNA, RNA,semisynthetic, synthetic origin, or any combinations thereof.

For purposes of the present invention, the degree of identity betweentwo nucleic acid sequences is determined as described above.

Modification of a nucleic acid sequence encoding a polypeptide of thepresent invention may be necessary for the synthesis of polypeptidessubstantially similar to the polypeptide. The term “substantiallysimilar” to the polypeptide refers to non-naturally occurring forms ofthe polypeptide. These polypeptides may differ in some engineered wayfrom the polypeptide isolated from its native source, e.g., variantsthat differ in specific activity, thermostability, pH optimum, or thelike. The variant sequence may be constructed on the basis of thenucleic acid sequence presented as the polypeptide encoding part of SEQID NO:1, e.g., a subsequence thereof, and/or by introduction ofnucleotide substitutions which do not give rise to another amino acidsequence of the polypeptide encoded by the nucleic acid sequence, butwhich correspond to the codon usage of the host organism intended forproduction of the enzyme, or by introduction of nucleotide substitutionswhich may give rise to a different amino acid sequence. For a generaldescription of nucleotide substitution, see, e.g., Ford et al., 1991,Protein Expression and Purification 2: 95-107.

It will be apparent to those skilled in the art that such substitutionscan be made outside the regions critical to the function of the moleculeand still result in an active polypeptide. Amino acid residues essentialto the activity of the polypeptide encoded by the isolated nucleic acidsequence of the invention, and therefore preferably not subject tosubstitution, may be identified according to procedures known in theart, such as site-directed mutagenesis or alanine-scanning mutagenesis(see, e.g., Cunningham and Wells, 1989, Science 244: 1081-1085). In thelatter technique, mutations are introduced at every positively chargedresidue in the molecule, and the resultant mutant molecules are testedfor arabinofuranosidase activity to identify amino acid residues thatare critical to the activity of the molecule. Sites of substrate-enzymeinteraction can also be determined by analysis of the three-dimensionalstructure as determined by such techniques as nuclear magnetic resonanceanalysis, crystallography or photoaffinity labelling (see, e.g., de Voset al., 1992, Science 255: 306-312; Smith et al., 1992, Journal ofMolecular Biology 224: 899-904; Wlodaver et al., 1992, FEBS Letters 309:59-64).

Nucleic Acid Constructs

The present invention also relates to nucleic acid constructs comprisinga nucleic acid sequence of the present invention operably linked to oneor more control sequences capable of directing the expression of thepolypeptide in a suitable host cell.

An isolated nucleic acid sequence encoding a polypeptide of the presentinvention may be manipulated in a variety of ways to provide forexpression of the polypeptide. Manipulation of the nucleic acid sequenceprior to its insertion into a vector may be desirable or necessarydepending on the expression vector. The techniques for modifying nucleicacid sequences utilizing recombinant DNA methods are well known in theart.

The control sequences include all components which are necessary oradvantageous for the expression of a polypeptide of the presentinvention. Each control sequence may be native or foreign to the nucleicacid sequence encoding the polypeptide. Such control sequences include,but are not limited to, a leader, polyadenylation sequence, propeptidesequence, promoter, signal peptide sequence, and transcriptionterminator. At a minimum, the control sequences include a promoter, andtranscriptional and translational stop signals. The control sequencesmay be provided with linkers for the purpose of introducing specificrestriction sites facilitating ligation of the control sequences withthe coding region of the nucleic acid sequence encoding a polypeptide.

The control sequence may be an appropriate promoter sequence, a nucleicacid sequence which is recognized by a host cell for expression of thenucleic acid sequence. The promoter sequence contains transcriptionalcontrol sequences which mediate the expression of the polypeptide. Thepromoter may be any nucleic acid sequence which shows transcriptionalactivity in the host cell of choice including mutant, truncated, andhybrid promoters, and may be obtained from genes encoding extracellularor intracellular polypeptides either homologous or heterologous to thehost cell.

Examples of suitable promoters for directing the transcription of thenucleic acid constructs of the present invention, especially in abacterial host cell, are the promoters obtained from the E. coli lacoperon, Streptomyces coelicolor agarase gene (dagA), Bacillus subtilislevansucrase gene (sacB), Bacillus licheniformis alpha-amylase gene(amyL), Bacillus stearothermophilus maltogenic amylase gene (amyM),Bacillus amyloliquefaciens alpha-amylase gene (amyQ), Bacilluslicheniformis penicillinase gene (penP), Bacillus subtilis xylA and xylBgenes, and prokaryotic beta-lactamase gene (Villa-Kamaroff et al., 1978,Proceedings of the National Academy of Sciences USA 75: 3727-3731), aswell as the tac promoter (DeBoer et al., 1983, Proceedings of theNational Academy of Sciences USA 80: 21-25). Further promoters aredescribed in “Useful proteins from recombinant bacteria” in ScientificAmerican, 1980, 242: 74-94; and in Sambrook et al., 1989, supra.

Examples of suitable promoters for directing the transcription of thenucleic acid constructs of the present invention in a filamentous fungalhost cell are promoters obtained from the genes for Aspergillus oryzaeTAKA amylase, Rhizomucor miehei aspartic proteinase, Aspergillus nigerneutral alpha-amylase, Aspergillus niger acid stable alpha-amylase,Aspergillus niger or Aspergillus awamori glucoamylase (glaA), Rhizomucormiehei lipase, Aspergillus oryzae alkaline protease, Aspergillus oryzaetriose phosphate isomerase, Aspergillus nidulans acetamidase, andFusarium oxysporum trypsin-like protease (WO 96/00787), as well as theNA2-tpi promoter (a hybrid of the promoters from the genes forAspergillus niger neutral alpha-amylase and Aspergillus oryzae triosephosphate isomerase), and mutant, truncated, and hybrid promotersthereof.

In a yeast host, useful promoters are obtained from the genes forSaccharomyces cerevisiae enolase (ENO-1), Saccharomyces cerevisiaegalactokinase (GAL1), Saccharomyces cerevisiae alcoholdehydrogenase/glyceraldehyde-3-phosphate dehydrogenase (ADH2/GAP), andSaccharomyces cerevisiae 3-phosphoglycerate kinase. Other usefulpromoters for yeast host cells are described by Romanos et al., 1992,Yeast 8: 423-488.

The control sequence may also be a suitable transcription terminatorsequence, a sequence recognized by a host cell to terminatetranscription. The terminator sequence is operably linked to the 3′terminus of the nucleic acid sequence encoding the polypeptide. Anyterminator which is functional in the host cell of choice may be used inthe present invention.

Preferred terminators for filamentous fungal host cells are obtainedfrom the genes for Aspergillus oryzae TAKA amylase, Aspergillus nigerglucoamylase, Aspergillus nidulans anthranilate synthase, Aspergillusniger alpha-glucosidase, and Fusarium oxysporum trypsin-like protease.

Preferred terminators for yeast host cells are obtained from the genesfor Saccharomyces cerevisiae enolase, Saccharomyces cerevisiaecytochrome C (CYC1), and Saccharomyces cerevisiaeglyceraldehyde-3-phosphate dehydrogenase. Other useful terminators foryeast host cells are described by Romanos et al., 1992, supra.

The control sequence may also be a suitable leader sequence, anontranslated region of an mRNA which is important for translation bythe host cell. The leader sequence is operably linked to the 5′ terminusof the nucleic acid sequence encoding the polypeptide. Any leadersequence that is functional in the host cell of choice may be used inthe present invention.

Preferred leaders for filamentous fungal host cells are obtained fromthe genes for Aspergillus oryzae TAKA amylase and Aspergillus nidulanstriose phosphate isomerase.

Suitable leaders for yeast host cells are obtained from the genes forSaccharomyces cerevisiae enolase (ENO-1), Saccharomyces cerevisiae3-phosphoglycerate kinase, Saccharomyces cerevisiae alpha-factor, andSaccharomyces cerevisiae alcoholdehydrogenase/glyceraldehyde-3-phosphate dehydrogenase (ADH2/GAP).

The control sequence may also be a polyadenylation sequence, a sequenceoperably linked to the 3′ terminus of the nucleic acid sequence andwhich, when transcribed, is recognized by the host cell as a signal toadd polyadenosine residues to transcribed mRNA. Any polyadenylationsequence which is functional in the host cell of choice may be used inthe present invention.

Preferred polyadenylation sequences for filamentous fungal host cellsare obtained from the genes for Aspergillus oryzae TAKA amylase,Aspergillus niger glucoamylase, Aspergillus nidulans anthranilatesynthase, Fusarium oxysporum trypsin-like protease, and Aspergillusniger alpha-glucosidase.

Useful polyadenylation sequences for yeast host cells are described byGuo and Sherman, 1995, Molecular Cellular Biology 15: 5983-5990.

The control sequence may also be a signal peptide coding region thatcodes for an amino acid sequence linked to the amino terminus of apolypeptide and directs the encoded polypeptide into the cell'ssecretory pathway. The 5′ end of the coding sequence of the nucleic acidsequence may inherently contain a signal peptide coding region naturallylinked in translation reading frame with the segment of the codingregion which encodes the secreted polypeptide. Alternatively, the 5′ endof the coding sequence may contain a signal peptide coding region whichis foreign to the coding sequence. The foreign signal peptide codingregion may be required where the coding sequence does not naturallycontain a signal peptide coding region. Alternatively, the foreignsignal peptide coding region may simply replace the natural signalpeptide coding region in order to enhance secretion of the polypeptide.However, any signal peptide coding region which directs the expressedpolypeptide into the secretory pathway of a host cell of choice may beused in the present invention.

Effective signal peptide coding regions for bacterial host cells are thesignal peptide coding regions obtained from the genes for Bacillus NCIB11837 maltogenic amylase, Bacillus stearothermophilus alpha-amylase,Bacillus licheniformis subtilisin, Bacillus licheniformisbeta-lactamase, Bacillus stearothermophilus neutral proteases (nprT,nprS, nprM), and Bacillus subtilis prsA. Further signal peptides aredescribed by Simonen and Palva, 1993, Microbiological Reviews 57:109-137.

Effective signal peptide coding regions for filamentous fungal hostcells are the signal peptide coding regions obtained from the genes forAspergillus oryzae TAKA amylase, Aspergillus niger neutral amylase,Aspergillus niger glucoamylase, Rhizomucor miehei aspartic proteinase,Humicola insolens cellulase, and Humicola lanuginosa lipase.

Useful signal peptides for yeast host cells are obtained from the genesfor Saccharomyces cerevisiae alpha-factor and Saccharomyces cerevisiaeinvertase. Other useful signal peptide coding regions are described byRomanos et al., 1992, supra.

The control sequence may also be a propeptide coding region that codesfor an amino acid sequence positioned at the amino terminus of apolypeptide. The resultant polypeptide is known as a proenzyme orpropolypeptide (or a zymogen in some cases). A propolypeptide isgenerally inactive and can be converted to a mature active polypeptideby catalytic or autocatalytic cleavage of the propeptide from thepropolypeptide. The propeptide coding region may be obtained from thegenes for Bacillus subtilis alkaline protease (aprE), Bacillus subtilisneutral protease (nprT), Saccharomyces cerevisiae alpha-factor,Rhizomucor miehei aspartic proteinase, and Myceliophthora thermophilalaccase (WO 95/33836).

Where both signal peptide and propeptide regions are present at theamino terminus of a polypeptide, the propeptide region is positionednext to the amino terminus of a polypeptide and the signal peptideregion is positioned next to the amino terminus of the propeptideregion.

It may also be desirable to add regulatory sequences which allow theregulation of the expression of the polypeptide relative to the growthof the host cell. Examples of regulatory systems are those which causethe expression of the gene to be turned on or off in response to achemical or physical stimulus, including the presence of a regulatorycompound. Regulatory systems in prokaryotic systems include the lac,tac, and trp operator systems. In yeast, the ADH2 system or GAL1 systemmay be used. In filamentous fungi, the TAKA alpha-amylase promoter,Aspergillus niger glucoamylase promoter, and Aspergillus oryzaeglucoamylase promoter may be used as regulatory sequences. Otherexamples of regulatory sequences are those which allow for geneamplification. In eukaryotic systems, these include the dihydrofolatereductase gene which is amplified in the presence of methotrexate, andthe metallothionein genes which are amplified with heavy metals. Inthese cases, the nucleic acid sequence encoding the polypeptide would beoperably linked with the regulatory sequence.

Expression Vectors

The present invention also relates to recombinant expression vectorscomprising a nucleic acid sequence of the present invention, a promoter,and transcriptional and translational stop signals. The various nucleicacid and control sequences described above may be joined together toproduce a recombinant expression vector which may include one or moreconvenient restriction sites to allow for insertion or substitution ofthe nucleic acid sequence encoding the polypeptide at such sites.Alternatively, the nucleic acid sequence of the present invention may beexpressed by inserting the nucleic acid sequence or a nucleic acidconstruct comprising the sequence into an appropriate vector forexpression. In creating the expression vector, the coding sequence islocated in the vector so that the coding sequence is operably linkedwith the appropriate control sequences for expression.

The recombinant expression vector may be any vector (e.g., a plasmid orvirus) which can be conveniently subjected to recombinant DNA proceduresand can bring about the expression of the nucleic acid sequence. Thechoice of the vector will typically depend on the compatibility of thevector with the host cell into which the vector is to be introduced. Thevectors may be linear or closed circular plasmids.

The vector may be an autonomously replicating vector, i.e., a vectorwhich exists as an extrachromosomal entity, the replication of which isindependent of chromosomal replication, e.g., a plasmid, anextrachromosomal element, a minichromosome, or an artificial chromosome.The vector may contain any means for assuring self-replication.Alternatively, the vector may be one which, when introduced into thehost cell, is integrated into the genome and replicated together withthe chromosome(s) into which it has been integrated. Furthermore, asingle vector or plasmid or two or more vectors or plasmids whichtogether contain the total DNA to be introduced into the genome of thehost cell, or a transposon may be used.

The vectors of the present invention preferably contain one or moreselectable markers which permit easy selection of transformed cells. Aselectable marker is a gene the product of which provides for biocide orviral resistance, resistance to heavy metals, prototrophy to auxotrophs,and the like. Examples of bacterial selectable markers are the dal genesfrom Bacillus subtilis or Bacillus licheniformis, or markers whichconfer antibiotic resistance such as ampicillin, kanamycin,chloramphenicol or tetracycline resistance. Suitable markers for yeasthost cells are ADE2, HIS3, LEU2, LYS2, MET3, TRP1, and URA3. Selectablemarkers for use in a filamentous fungal host cell include, but are notlimited to, amdS (acetamidase), argB (ornithine carbamoyltransferase),bar (phosphinothricin acetyltransferase), hygB (hygromycinphosphotransferase), niaD (nitrate reductase), pyrG(orotidine-5′-phosphate decarboxylase), sC (sulfate adenyltransferase),trpC (anthranilate synthase), as well as equivalents thereof. Preferredfor use in an Aspergillus cell are the amdS and pyrG genes ofAspergillus nidulans or Aspergillus oryzae and the bar gene ofStreptomyces hygroscopicus.

The vectors of the present invention preferably contain an element(s)that permits stable integration of the vector into the host cell'sgenome or autonomous replication of the vector in the cell independentof the genome.

For integration into the host cell genome, the vector may rely on thenucleic acid sequence encoding the polypeptide or any other element ofthe vector for stable integration of the vector into the genome byhomologous or nonhomologous recombination. Alternatively, the vector maycontain additional nucleic acid sequences for directing integration byhomologous recombination into the genome of the host cell. Theadditional nucleic acid sequences enable the vector to be integratedinto the host cell genome at a precise location(s) in the chromosome(s).To increase the likelihood of integration at a precise location, theintegrational elements should preferably contain a sufficient number ofnucleic acids, such as 100 to 1,500 base pairs, preferably 400 to 1,500base pairs, and most preferably 800 to 1,500 base pairs, which arehighly homologous with the corresponding target sequence to enhance theprobability of homologous recombination. The integrational elements maybe any sequence that is homologous with the target sequence in thegenome of the host cell.

Furthermore, the integrational elements may be non-encoding or encodingnucleic acid sequences. On the other hand, the vector may be integratedinto the genome of the host cell by non-homologous recombination.

For autonomous replication, the vector may further comprise an origin ofreplication enabling the vector to replicate autonomously in the hostcell in question. Examples of bacterial origins of replication are theorigins of replication of plasmids pBR322, pUC19, pACYC177, and pACYC184permitting replication in E. coli, and pUB110, pE194, pTA1060, and pAMβ1permitting replication in Bacillus. Examples of origins of replicationfor use in a yeast host cell are the 2 micron origin of replication,ARS1, ARS4, the combination of ARS1 and CEN3, and the combination ofARS4 and CEN6. The origin of replication may be one having a mutationwhich makes its functioning temperature-sensitive in the host cell (see,e.g., Ehrlich, 1978, Proceedings of the National Academy of Sciences USA75: 1433).

More than one copy of a nucleic acid sequence of the present inventionmay be inserted into the host cell to increase production of the geneproduct. An increase in the copy number of the nucleic acid sequence canbe obtained by integrating at least one additional copy of the sequenceinto the host cell genome or by including an amplifiable selectablemarker gene with the nucleic acid sequence where cells containingamplified copies of the selectable marker gene, and thereby additionalcopies of the nucleic acid sequence, can be selected for by cultivatingthe cells in the presence of the appropriate selectable agent.

The procedures used to ligate the elements described above to constructthe recombinant expression vectors of the present invention are wellknown to one skilled in the art (see, e.g., Sambrook et al., 1989,supra).

Host Cells

The present invention also relates to recombinant host cells, comprisinga nucleic acid sequence of the invention, which are advantageously usedin the recombinant production of the polypeptides.

A vector comprising a nucleic acid sequence of the present invention isintroduced into a host cell so that the vector is maintained as achromosomal integrant or as a self-replicating extra-chromosomal vectoras described earlier. The choice of a host cell will to a large extentdepend upon the gene encoding the polypeptide and its source.

The host cell may be a unicellular microorganism, e.g., a prokaryote, ora non-unicellular microorganism, e.g., a eukaryote.

Useful unicellular cells are bacterial cells such as gram positivebacteria including, but not limited to, a Bacillus cell, e.g., Bacillusalkalophilus, Bacillus amyloliquefaciens, Bacillus brevis, Bacilluscirculans, Bacillus clausii, Bacillus coagulans, Bacillus lautus,Bacillus lentus, Bacillus licheniformis, Bacillus megaterium, Bacillusstearothermophilus, Bacillus subtilis, and Bacillus thuringiensis; or aStreptomyces cell, e.g., Streptomyces lividans or Streptomyces murinus,or gram negative bacteria such as E. coli and Pseudomonas sp. In apreferred embodiment, the bacterial host cell is a Bacillus lentus,Bacillus licheniformis, Bacillus stearothermophilus, or Bacillussubtilis cell. In another preferred embodiment, the Bacillus cell is analkalophilic Bacillus.

The introduction of a vector into a bacterial host cell may, forinstance, be effected by protoplast transformation (see, e.g., Chang andCohen, 1979, Molecular General Genetics 168: 111-115), using competentcells (see, e.g., Young and Spizizin, 1961, Journal of Bacteriology 81:823-829, or Dubnau and Davidoff-Abelson, 1971, Journal of MolecularBiology 56: 209-221), electroporation (see, e.g., Shigekawa and Dower,1988, Biotechniques 6: 742-751), or conjugation (see, e.g., Koehler andThorne, 1987, Journal of Bacteriology 169: 5771-5278). The host cell maybe a eukaryote, such as a mammalian, insect, plant, or fungal cell.

In a preferred embodiment, the host cell is a fungal cell. “Fungi” asused herein includes the phyla Ascomycota, Basidiomycota,Chytridiomycota, and Zygomycota (as defined by Hawksworth et al., In,Ainsworth and Bisby's Dictionary of The Fungi, 8th edition, 1995, CABInternational, University Press, Cambridge, UK) as well as the Oomycota(as cited in Hawksworth et al., 1995, supra, page 171) and allmitosporic fungi (Hawksworth et al., 1995, supra).

In a more preferred embodiment, the fungal host cell is a yeast cell.“Yeast” as used herein includes ascosporogenous yeast (Endomycetales),basidiosporogenous yeast, and yeast belonging to the Fungi Imperfecti(Blastomycetes). Since the classification of yeast may change in thefuture, for the purposes of this invention, yeast shall be defined asdescribed in Biology and Activities of Yeast (Skinner, F. A., Passmore,S. M., and Davenport, R. R., eds, Soc. App. Bacteriol. Symposium SeriesNo. 9, 1980).

In an even more preferred embodiment, the yeast host cell is a Candida,Hansenula, Kluyveromyces, Pichia, Saccharomyces, Schizosaccharomyces, orYarrowia cell.

In a most preferred embodiment, the yeast host cell is a Saccharomycescarlsbergensis, Saccharomyces cerevisiae, Saccharomyces diastaticus,Saccharomyces douglasii, Saccharomyces kluyveri, Saccharomyces norbensisor Saccharomyces oviformis cell. In another most preferred embodiment,the yeast host cell is a Kluyveromyces lactis cell. In another mostpreferred embodiment, the yeast host cell is a Yarrowia lipolytica cell.

In another more preferred embodiment, the fungal host cell is afilamentous fungal cell. “Filamentous fungi” include all filamentousforms of the subdivision Eumycota and Oomycota (as defined by Hawksworthet al., 1995, supra). The filamentous fungi are characterized by amycelial wall composed of chitin, cellulose, glucan, chitosan, mannan,and other complex polysaccharides. Vegetative growth is by hyphalelongation and carbon catabolism is obligately aerobic. In contrast,vegetative growth by yeasts such as Saccharomyces cerevisiae is bybudding of a unicellular thallus and carbon catabolism may befermentative.

In an even more preferred embodiment, the filamentous fungal host cellis a cell of a species of, but not limited to, Acremonium, Aspergillus,Fusarium, Humicola, Mucor, Myceliophthora, Neurospora, Penicillium,Thielavia, Tolypocladium, or Trichoderma.

In a most preferred embodiment, the filamentous fungal host cell is anAspergillus awamori, Aspergillus foetidus, Aspergillus japonicus,Aspergillus nidulans, Aspergillus niger or Aspergillus oryzae cell. Inanother most preferred embodiment, the filamentous fungal host cell is aFusarium bactridioides, Fusarium cerealis, Fusarium crookwellense,Fusarium culmorum, Fusarium graminearum, Fusarium graminum, Fusariumheterosporum, Fusarium negundi, Fusarium oxysporum, Fusariumreticulatum, Fusarium roseum, Fusarium sambucinum, Fusarium sarcochroum,Fusarium sporotrichioides, Fusarium suiphureum, Fusarium torulosum,Fusarium trichothecioides, or Fusarium venenatum cell. In an even mostpreferred embodiment, the filamentous fungal parent cell is a Fusariumvenenatum (Nirenberg sp. nov.) cell. In another most preferredembodiment, the filamentous fungal host cell is a Humicola insolens,Humicola lanuginosa, Mucor miehei, Myceliophthora thermophila,Neurospora crassa, Penicillium purpurogenum, Thielavia terrestris,Trichoderma harzianum, Trichoderma koningii, Trichodermalongibrachiatum, Trichoderma reesei, or Trichoderma viride cell.

Fungal cells may be transformed by a process involving protoplastformation, transformation of the protoplasts, and regeneration of thecell wall in a manner known per se. Suitable procedures fortransformation of Aspergillus host cells are described in EP 238 023 andYelton et al., 1984, Proceedings of the National Academy of Sciences USA81: 1470-1474. Suitable methods for transforming Fusarium species aredescribed by Malardier et al., 1989, Gene 78: 147-156 and WO 96/00787.Yeast may be transformed using the procedures described by Becker andGuarente, In Abelson, J. N. and Simon, M. I., editors, Guide to YeastGenetics and Molecular Biology, Methods in Enzymology, Volume 194, pp182-187, Academic Press, Inc., New York; Ito et al., 1983, Journal ofBacteriology 153: 163; and Hinnen et al., 1978, Proceedings of theNational Academy of Sciences USA 75: 1920.

Methods of Production

The present invention also relates to methods for producing apolypeptide of the present invention, the method comprising (a)cultivating a strain from the genus Humicola or the genus Meripilus. toproduce a supernatant comprising the polypeptide; and (b) recovering thepolypeptide. Preferably, the strain is of the species Humicola insolensor the species Meripilus giganteus.

The present invention also relates to a method for producing apolypeptide of the invention, the method comprising (a) cultivating arecombinant host cell as described above under conditions conducive tothe production of the polypeptide, and (b) recovering the polypeptidefrom the cells and/or the culture medium.

In the production methods of the present invention, the cells arecultivated in a nutrient medium suitable for production of thepolypeptide using methods known in the art. For example, the cell may becultivated by shake flask cultivation, small-scale or large-scalefermentation (including continuous, batch, fed-batch, or solid statefermentations) in laboratory or industrial fermentors performed in asuitable medium and under conditions allowing the polypeptide to beexpressed and/or isolated. The cultivation takes place in a suitablenutrient medium comprising carbon and nitrogen sources and inorganicsalts, using procedures known in the art. Suitable media are availablefrom commercial suppliers or may be prepared according to publishedcompositions (e.g., in catalogues of the American Type CultureCollection). If the polypeptide is secreted into the nutrient medium,the polypeptide can be recovered directly from the medium. If thepolypeptide is not secreted, it can be recovered from cell lysates.

The polypeptides may be detected using methods known in the art that arespecific for the polypeptides. These detection methods may include useof specific antibodies, formation of an enzyme product, or disappearanceof an enzyme substrate. For example, an enzyme assay may be used todetermine the activity of the polypeptide as described herein.

The resulting polypeptide may be recovered by methods known in the art.For example, the polypeptide may be recovered from the nutrient mediumby conventional procedures including, but not limited to,centrifugation, filtration, extraction, spray-drying, evaporation, orprecipitation.

The polypeptides of the present invention may be purified by a varietyof procedures known in the art including, but not limited to,chromatography (e.g., ion exchange, affinity, hydrophobic,chromatofocusing, and size exclusion), electrophoretic procedures (e.g.,preparative isoelectric focusing), differential solubility (e.g.,ammonium sulfate precipitation), SDS-PAGE, or extraction (see, e.g.,Protein Purification, J.-C. Janson and Lars Ryden, editors, VCHPublishers, New York, 1989).

Expression of the Enzymes in Plants

A DNA sequence encoding a polypeptide of interest, such as anarabinofuranosidase of the present invention, may be transformed andexpressed in transgenic plants as described below.

The transgenic plant can be dicotyledonous or monocotyledonous, forshort a dicot or a monocot. Examples of monocot plants are grasses, suchas meadow grass (blue grass, Poa), forage grass such as Festuca, Lolium,temperate grass, such as Agrostis, and cereals, e.g. wheat, oats, rye,barley, rice, sorghum and maize (corn).

Examples of dicot plants are tobacco, legumes, such as lupins, potato,sugar beet, pea, bean and soybean, and cruciferous plants (familyBrassicaceae), such as cauliflower, oil seed rape and the closelyrelated model organism Arabidopsis thaliana.

Examples of plant parts are stem, callus, leaves, root, fruits, seeds,and tubers as well as the individual tissues comprising these parts,e.g. epidermis, mesophyll, parenchyme, vascular tissues, meristems. Inthe present context, also specific plant cell compartments, such aschloroplast, apoplast, mitochondria, vacuole, peroxisomes and cytoplasmare considered to be a plant part. Furthermore, any plant cell, whateverthe tissue origin, is considered to be a plant part. Likewise, plantparts such as specific tissues and cells isolated to facilitate theutilisation of the invention are also considered plant parts e.g.embryos, endosperms, aleurone and seeds coats.

Also included within the scope of the invention are the progeny of suchplants, plant parts and plant cells.

The transgenic plant or plant cell expressing the polypeptide ofinterest may be constructed in accordance with methods known in the art.In short the plant or plant cell is constructed by incorporating one ormore expression constructs encoding the polypeptide of interest into theplant host genome and propagating the resulting modified plant or plantcell into a transgenic plant or plant cell.

Conveniently, the expression construct is a DNA construct whichcomprises a gene encoding the polypeptide of interest in operableassociation with appropriate regulatory sequences required forexpression of the gene in the plant or plant part of choice.Furthermore, the expression construct may comprise a selectable markeruseful for identifying host cells into which the expression constructhas been integrated and DNA sequences necessary for introduction of theconstruct into the plant in question (the latter depends on the DNAintroduction method to be used).

The choice of regulatory sequences, such as promoter and terminatorsequences and optionally signal or transit sequences is determined, e.g.on the basis of when, where and how the enzyme is desired to beexpressed. For instance, the expression of the gene encoding the enzymeof the invention may be constitutive or inducible, or may bedevelopmental, stage or tissue specific, and the gene product may betargeted to a specific cell compartment, tissue or plant part such asseeds or leaves. Regulatory sequences are, e.g. described by Tague etal, Plant, Phys., 86, 506, 1988.

For constitutive expression the 35S-CaMV, the maize ubiquitin 1 and therice actin 1 promoter may be used (Franck et al. 1980. Cell 21: 285-294,Christensen A H, Sharrock R A and Quail 1992. Maize polyubiquitin genes:structure, thermal perturbation of expression and transcript splicing,and promoter activity following transfer to protoplasts byelectroporation. Plant Mo. Biol. 18, 675-689.; Zhang W, McElroy D. andWu R 1991, Analysis of rice Act1 5′ region activity in transgenic riceplants. Plant Cell 3, 1155-1165). Organ-specific promoters may, e.g. bea promoter from storage sink tissues such as seeds, potato tubers, andfruits (Edwards & Coruzzi, 1990. Annu. Rev. Genet. 24: 275-303), or frommetabolic sink tissues such as meristems (Ito et al., 1994. Plant Mol.Biol. 24: 863-878), a seed specific promoter such as the glutelin,prolamin, globulin or albumin promoter from rice (Wu et al., Plant andCell Physiology Vol. 39, No. 8 pp. 885-889 (1998)), a Vicia fabapromoter from the legumin B4 and the unknown seed protein gene fromVicia faba described by Conrad U. et al, Journal of Plant PhysiologyVol. 152, No. 6 pp. 708-711 (1998), a promoter from a seed oil bodyprotein (Chen et al., Plant and cell physiology vol. 39, No. 9 pp.935-941 (1998), the storage protein napA promoter from Brassica napus,or any other seed specific promoter known in the art, e.g. as describedin WO 91/14772. Furthermore, the promoter may be a leaf specificpromoter such as the rbcs promoter from rice or tomato (Kyozuka et al.,Plant Physiology Vol. 102, No. 3 pp. 991-1000 (1993), the chlorellavirus adenine methyltransferase gene promoter (Mitra, A. and Higgins, DW, Plant Molecular Biology Vol. 26, No. 1 pp. 85-93 (1994), or the aldPgene promoter from rice (Kagaya et al., Molecular and General GeneticsVol. 248, No. 6 pp. 668-674 (1995), or a wound inducible promoter suchas the potato pin2 promoter (Xu et al, Plant Molecular Biology Vol. 22,No. 4 pp. 573-588 (1993). Likewise, the promoter may inducible byabiotic treatments such as temperature, drought or alterations insalinity or induced by exogenously applied substances that activate thepromoter e.g. ethanol, oestrogens, plant hormones like ethylene,abscisic acid and gibberellic acid and heavy metals.

A promoter enhancer element may be used to achieve higher expression ofthe enzyme in the plant. For instance, the promoter enhancer element maybe an intron which is placed between the promoter and the nucleotidesequence encoding the enzyme. For instance, Xu et al. op cit disclosethe use of the first intron of the rice actin 1 gene to enhanceexpression.

The selectable marker gene and any other parts of the expressionconstruct may be chosen from those available in the art.

The DNA construct is incorporated into the plant genome according toconventional techniques known in the art, includingAgrobacterium-mediated transformation, virus-mediated transformation,micro injection, particle bombardment, biolistic transformation, andelectroporation (Gasser et al, Science, 244, 1293; Potrykus, Bio/Techn.8, 535, 1990; Shimamoto et al, Nature, 338, 274, 1989).

Presently, Agrobacterium tumefaciens mediated gene transfer is themethod of choice for generating transgenic dicots (for review Hooykas &Schilperoort, 1992. Plant Mol. Biol. 19: 15-38), and can also be usedfor transforming monocots, although other transformation methods oftenare used for these plants. Presently, the method of choice forgenerating transgenic monocots supplementing the Agrobacterium approachis particle bombardment (microscopic gold or tungsten particles coatedwith the transforming DNA) of embryonic calli or developing embryos(Christou, 1992. Plant J. 2: 275-281; Shimamoto, 1994. Curr. Opin.Biotechnol. 5: 158-162; Vasil et al., 1992. Bio/Technology 10: 667-674).An alternative method for transformation of monocots is based onprotoplast transformation as described by Omirulleh S, et al., PlantMolecular biology Vol. 21, No. 3 pp. 415-428 (1993).

Following transformation, the transformants having incorporated theexpression construct are selected and regenerated into whole plantsaccording to methods well-known in the art. Often the transformationprocedure is designed for the selective elimination of selection geneseither during regeneration or in the following generations by using e.g.co-transformation with two separate T-DNA constructs or site specificexcision of the selection gene by a specific recombinase.

Use of Arabinofuranosidases

The present invention also relates to use of the polypeptides of theinvention, i.e. the arabinofuranosidases, in various industrialapplication, e.g. in biomass conversion, such as in production of fuelethanol from cellulose containing biomass, in production of fuel and/orpotable ethanol from starch, in mashing for beer production, in a doughfor bread making, or in manufacture of an animal feed product.

The invention furthermore provides a process wherein a arabinoxylancontaining substrate and/or a biomass is contacted with anarabinofuranosidase capable of releasing arabinose from di-substitutedxyloses. Preferably the alpha-L-arabinofuranosidase is anarabinofuranosidase of GH43. The alpha-L-arabinofuranosidase of GH43 ispreferably derived of bacterial, of fungal or of plant origin.Preferably the arabinoxylan containing substrate and/or the biomass isselected from the list consisting of herbaceous and/or woody energycrops, agricultural food and feed crops, animal feed products, tubers,roots, stems, legumes, cassava peels, cocoa pods, rice husks and/orhulls, rice bran from rice polishing, cobs, straw, hulls and/or husksfrom cereal grain, pressed sugar cane stalk, sugar beet pulp, locustbean pulp, vegetable or fruit pomaces, cereals or whole grainagricultural crop waste, straw, stalks, leaves, corn bran, husks, cobs,rind, shells, pods, wood waste, bark, shavings, sawdust, wood pulp,pulping liquor, waste paper, cardboard, construction and demolition woodwaste, industrial or municipal waste water solids or sludge, manure,by-product from brewing and/or fermentation processes, wet distillersgrain, dried distillers grain, spent grain, vinasse and bagasse.

The present invention also relates to compositions comprising thepolypeptides of the invention, i.e. the arabinofuranosidase, as well asto uses of such compositions.

Materials and Methods

Arabinose and xylose were purchased from Merck (Darmstadt, Germany).Water soluble and water insoluble wheat arabinoxylans were obtained fromMegazyme (Bray, County Wicklow, Ireland).

Enzymes

The alpha-L-arabinofuranosidases were cloned using basic moleculartechniques (Sambrook et al., 1989, Molecular Cloning, A LaboratoryManual, 2d edition, Cold Spring Harbor, N.Y., Christgau et al. 1995,Curr. Genet. 27, 135-141, Ausubel et al., 2003, Curr. Prot. Mol. Biol.,John Wiley & Sons, Cambridge, USA,).

The Bifidobacterium adolescentis alpha-L-arabinofuranosidases of VanLaere et al. (1997) and Van den Broek et al. (2005) was obtained fromMegazyme (Ireland).

Shearzyme (GH10) and Pentopan Mono (GH11), monocomponentendo-1,4-β-xylanase preparations produced by Aspergillus aculeatus andThermomyces lanuginosus, respectively, were commercial products fromNovozymes A/S (Bagsvrd, Denmark).

Preparation of Specific Arabinoxylan Polymers and Oligosaccharides

Doubly substituted arabinoxylan was prepared by incubating soluble wheatarabinoxylan (1 g) in 0.1M acetate buffer (100 mL), pH 6.0 with 0.167 gα-L-arabinofuranosidase from Meripilus giganteus (GH51)·kg⁻¹ watersoluble wheat arabinoxylan for 48 hours at 30° C. Singly substitutedarabinoxylan was prepared by incubating water soluble wheat arabinoxylan(1 g) in 0.1M acetate buffer (42 mL), pH 6.0 with 0.147 gα-L-arabinofuranosidase from Humicola insolens (GH43)·kg⁻¹ water solublewheat arabinoxylan for 48 hours at 30° C. To halt the enzymaticreactions the mixtures were heated to 100° C. for 10 min. Arabinoxylanpolymers were precipitated by addition of ethanol (126 ml). Theprecipitates were filtered (Miracloth) and dryed in vacuum

Oligosaccharides containing arabinosyl groups linked to terminal (1→3)were prepared by incubating the water insoluble wheat arabinoxylan (1 g)in 0.1M acetate buffer (100 mL), pH 6.0 with 6.67 g Shearzyme (xylanaseGH10)·kg⁻¹ water insoluble wheat arabinoxylan for 2 hours at 30° C.Oligosaccharides containing arabinosyl groups linked to internal (1→3)were prepared by incubating water insoluble wheat arabinoxylan (1 g) in0.1M acetate buffer (100 mL), pH 6.0 with 0.03 g Pentopan Mono (xylanaseGH11)·kg⁻¹ water insoluble wheat arabinoxylan for 2 hours at 30° C.Oligosaccharides containing arabinosyl groups linked to internal (1→2)were prepared by incubating water insoluble wheat arabinoxylan (1 g) in0.1M acetate buffer (100 mL), pH 6.0 with 0.03 g Pentopan Mono (xylanaseGH11)·kg⁻¹ water insoluble wheat arabinoxylan andalpha-L-arabinofuranosidase from H. insolens (GH43)·kg⁻¹ water solublewheat arabinoxylan for 2 hours at 30° C. To halt the enzymatic reactionsthe mixtures were heated to 100° C. for 10 min. Thearabinoxylo-oligosaccharides were concentrated on a rotary evaporatorand evaluated by ¹H-NMR.

Assay for Activity Towards Alpha-L-Arabinofuranosidase Activity

Alpha-L-arabinofuranosidase activity may be assessed as described byPoutanen et al. (Appl. Microbiol. Biotechnol. 1988, 28, 425-432) using 5mM p-nitrophenyl alpha-L-arabinofuranoside as substrates. The reactionsmay be carried out in 50 mM citrate buffer at pH 6.0, 40° C. with atotal reaction time of 30 min. The reaction is stopped by adding 0.5 mlof 1M sodium carbonate and the liberated p-nitrophenol is measured at405 nm. Activity is expressed in U/ml.

Assay for Activity Towards C2- and C3-Di-Substituted Xylan

Medium viscosity water-soluble wheat arabinoxylan (Megazyme, Bray,Ireland) was treated with an alpha-arabinofuranosidase of GH51 fromMeripilus giganteus (SEQ ID NO:2) to remove singlealpha-arabinofuranosyl substituents attached to the C(O)-3 arabinose ofthe arabinoxylan in order to produce an di-substituted arabinoxylansubstrate with arabinofuranosyl substituents attached to both C(O)-2,3of the xylose residues. The substrate was dialysed and freeze dried.

A 0.1% solution of the di-substituted arabinoxylan was prepared and thealpha-arabinofuranosidase activity was measured by mixing 0.1 ml enzyme,0.9 ml buffer (0.12M Succinic acid, pH 6.0) and 1.0 ml substratesolution in an eppendorf tube. The eppendorf tube was incubated at 60°C. for 1 hour with shaking. The amount of liberated arabinose wasmeasured by HPAEC (high-performance anion-exchange chromatography).

HPAEC

Hydrolysates (10 μl) were applied onto a Dionex BioLC system fitted witha Dionex CarboPac™ PA1 guard column (4×250 mm) (Dionex Corporation,Sunnyvale, Calif., USA) combined with a CarboPac™ PA1 precolumn (4×50mm). The monosaccharides were separated isocratically with 10 mM KOH for15 min, flow: 1 Monosaccharides were detected by a pulsedelectrochemical detector in the pulsed amperiometric detection mode. Thepotential of the electrode was programmed for +0.1 V (t=0-0.4 s) to −2.0V (t=0.41-0.42 s) to 0.6 V (t=0.43 s) and finally −0.1 V (t=0.44-0.50s), while integrating the resulting signal from t=0.2-0.4 s. A mixtureof arabinose and xylose (concentration of each component: 0.0025-0.1g·L⁻¹) was used as standard.

¹H-NMR Analysis

All degradation products were lyophilized twice from 99.9% D₂O andre-dissolved in 99.9% D₂O. Some hydrolysates were dialyzed (Spectra/Pormembrane molecular weight cut-off 1000) to remove free arabinose priorto the spectral analysis. The ¹H-NMR spectra were recorded at 30° C. ina Varian Mercury-VX instrument operated at 400 MHz and equipped with a4-nucleus auto-switchable probe. Data were collected over 128-512 scansand the HDO signal was used as a reference signal (4.67 ppm).

EXAMPLES Example 1

Wheat arabinoxylan comprises arabinofuranoside as a monosubstituentlinked to the 3-position of internal xylose (A) and arabinofuranosidelinked to the 3- (B) and 2-position (C) on di-substituted xylose,respectively. Substrates were produced each comprising only one of the 3types of arabinofuranoside linkages. The activity ofarabinofuranosidases towards these substrates was investigated using ¹HNMR.

TABLE 1 Origin, families, and molecular mass of alpha-L-arabinofuranosidase activities Origin Family Mol mass (kDa) H. insolens(SEQ ID NO: 2) GH43 ~62 M. giganteus (SEQ ID NO: 4) GH51 ~69 B.adolescentis GH43 ~60 H. insolens GH51 ~94

TABLE 2 Activity on selected arabinoxylan polymers, incubation at pH 6,40° C. for 2 hrs. Enzyme H. insolens B. adolescentis H. insolens M.giganteus Substrate Linkage (GH43) (GH43) (GH51) (GH51) IntactMono-substituted — — x xx arabinoxylan (1→3) Di-substituted — — — —(1→2) Di-substituted xx x — — (1→3) Di- Di-substituted — — — —substituted (1→2) arabinoxylan Di-substituted xx xx — — (1→3) Mono-Mono-substituted — — xx xx substituted (1→2) arabinoxylanMono-substituted — — xx xx (1→3) xx refers to more than 75% hydrolysis,x(x) to 50-75% hydrolysis, x to 25-50% hydrolysis and (x) to 5-25%hydrolysis. — refers to no detectable hydrolysis

Example 2

Soluble wheat arabinoxylan was incubated with 0.1 g enzyme protein perkg DM of alpha-L-arabinofuranosidase from H. insolens (GH43), B.adolescentis (GH43), H. insolens (GH51), and M. giganteus (GH51) for 24hrs. The released arabinose was measured. Results are expressed in mgarabinose per g water soluble wheat arabinoxylan, as the average oftriplicate determinations, coefficient of variation on mean <6.4.

TABEL 3 Released arabinose from soluble wheat arabinoxylan treated withalpha- L-arabinofuranosidase. Reaction conditions Origin pH 6, 40° C. pH5, 50° C. H. insolens (GH43) 128.0 a  147.0 a M. giganteus (GH51) 48.15c 121.0 b B. adolescentis (GH43) 63.43 b   4.833 d H. insolens (GH51)20.75 d  18.47 c

Example 3

Arabionofuranosidases may be applied in animal feed compositions toincrease digestibility. Corn arabinoxylan is heavily di-substituted witharabinose. In order to facilitate the xylan degradation it isadvantageous to remove as many as possible of the arabinosesubstituents. The in vitro degradation of arabinoxylans in a corn baseddiet supplemented with the GH51 arabinofuranosidase from Humicolainsolens and a commercial xylanase derived from Termomyces lanuginosuswas studied in an in vitro digestion system.

Conditions for the Vitro Digestion System:

-   -   Substrate: 800 mg 30:70 Soy bean meal/Corn diet milled and        pre-blended    -   pH: pH 5, 4 and 3 (gastric) and 4.0 (transition step) followed        by a small intestinal step at pH 6.8    -   Pepsin: 3000 U/g diet.    -   Pancreatin 8 mg/g diet    -   Temperature: 40° C.    -   Number of replicates: 4    -   Enzyme dosage: Arabinofuranosidase and xylanase 50 and 67 mg        EP/kg diet respectively

Samples were precipitated with 80% ethanol, centrifuged and supernatantdiscarded. The pellet was washed in 80% ethanol and centrifuged andsupernatant discarded. The pellet was dissolved in acetate buffer (pH 5)and starch was removed before dietary fibre analysis.

TABLE 4 Content of arabinose and xylose in residual total non-starchpolysaccharide residues after in vitro digestion Non-starchpolysaccharide residues (% of dry matter) Arabinose Xylose Control 1.78a2.06a Arabinofuranosidase from Humicola insolens 1.71a 1.93a Xylanasefrom Thermomyces lanuginosus 1.68a 1.81b Xylanase + arabinofuranosidase1.60b 1.78b Average values within a column not sharing a common letterindex differ with statistical significance (P <0.05).

1-18. (canceled)
 19. A nucleic acid construct comprising a nucleic acid sequence encoding a polypeptide having arabinofuranosidase activity, wherein the nucleic acid sequence is operably linked to one or more heterologous control sequences capable of directing the expression of the polypeptide in a suitable expression host, and wherein the polypeptide having arabinofuranosidase activity is selected from the group consisting of: (a) a polypeptide with at least 95% sequence identity to the mature polypeptide of SEQ ID NO: 4; and (b) a polypeptide which is encoded by a nucleic acid sequence which hybridizes under high stringency conditions with the full-length complement of the nucleic acid sequence of nucleotides 46 to 1974 of SEQ ID NO: 3; wherein the high stringency conditions are defined as prehybridization and hybridization at 42° C. in 5×SSPE, 0.3% SDS, 200 micrograms/mL sheared and denatured salmon sperm DNA, and 50% formamide for high stringency, following standard Southern blotting procedures, followed by washing three times each for 15 minutes using 2×SSC, 0.2% SDS at 65° C.
 20. The nucleic acid construct of claim 19, wherein the polypeptide has at least 95% sequence identity to the mature polypeptide of SEQ ID NO:
 4. 21. The nucleic acid construct of claim 19, wherein the polypeptide has at least 97% sequence identity to the mature polypeptide of SEQ ID NO:
 4. 22. The nucleic acid construct of claim 19, wherein the polypeptide comprises the mature polypeptide of SEQ ID NO:
 4. 23. The nucleic acid construct of claim 19, wherein the polypeptide is encoded by a nucleic acid sequence which hybridizes under very high stringency conditions with the full-length complement of the nucleic acid sequence of nucleotides 46 to 1974 of SEQ ID NO: 3; wherein the very high stringency conditions are defined as prehybridization and hybridization at 42° C. in 5×SSPE, 0.3% SDS, 200 micrograms/mL sheared and denatured salmon sperm DNA, and 50% formamide for high stringency, following standard Southern blotting procedures, followed by washing three times each for 15 minutes using 2×SSC, 0.2% SDS at 70° C.
 24. The nucleic acid construct of claim 19, wherein the polypeptide is a fragment of the mature polypeptide of SEQ ID NO: 4 and has arabinofuranosidase (EC 3.2.1.55) activity, wherein the fragment has one or more amino acids deleted from the amino and/or carboxyl terminus of the mature polypeptide of SEQ ID NO: 4 and has at least 430 amino acids of the mature polypeptide of SEQ ID NO:
 4. 25. The nucleic acid construct of claim 19, wherein the polypeptide is native to a strain of Meripilus.
 26. The nucleic acid construct of claim 19, wherein the polypeptide is native to a strain of Meripilus giganteus.
 27. The nucleic acid construct of claim 19, wherein the polypeptide comprises the mature polypeptide of SEQ ID NO: 4 and exhibits arabinofuranosidase activity.
 28. A recombinant expression vector comprising the nucleic acid construct of claim
 19. 29. A recombinant host cell transformed with the nucleic acid construct of claim
 19. 30. A method for producing a polypeptide having arabinofuranosidase activity, comprising cultivating the recombinant host cell of claim 29 under conditions conducive for production of the polypeptide, and recovering the polypeptide.
 31. A recombinant host cell transformed with a nucleic acid sequence encoding a polypeptide having arabinofuranosidase activity, wherein the polypeptide is selected from the group consisting of: (a) a polypeptide with at least 95% sequence identity to the mature polypeptide of SEQ ID NO: 4; and (b) a polypeptide which is encoded by a nucleic acid sequence which hybridizes under high stringency conditions with the full complement of the nucleic acid sequence of nucleotides 46 to 1974 of SEQ ID NO: 3; wherein the high stringency conditions are defined as prehybridization and hybridization at 42° C. in 5×SSPE, 0.3% SDS, 200 micrograms/mL sheared and denatured salmon sperm DNA, and 50% formamide for high stringency, following standard Southern blotting procedures, followed by washing three times each for 15 minutes using 2×SSC, 0.2% SDS at 65° C., and wherein the polypeptide exhibits arabinofuranosidase activity.
 32. The recombinant host cell of claim 31, wherein the polypeptide has at least 95% sequence identity to the mature polypeptide of SEQ ID NO:
 4. 33. The recombinant host cell of claim 31, wherein the polypeptide has at least 97% sequence identity to the mature polypeptide of SEQ ID NO:
 4. 34. The recombinant host cell of claim 31, wherein the polypeptide comprises the mature polypeptide of SEQ ID NO:
 4. 35. The recombinant host cell of claim 31, wherein the polypeptide is encoded by a nucleic acid sequence which hybridizes under very high stringency conditions with the full-length complement of the nucleic acid sequence of nucleotides 46 to 1974 of SEQ ID NO: 3; wherein the very high stringency conditions are defined as prehybridization and hybridization at 42° C. in 5×SSPE, 0.3% SDS, 200 micrograms/mL sheared and denatured salmon sperm DNA, and 50% formamide for high stringency, following standard Southern blotting procedures, followed by washing three times each for 15 minutes using 2×SSC, 0.2% SDS at 70° C.
 36. The recombinant host cell of claim 31, wherein the polypeptide is a fragment of the mature polypeptide of SEQ ID NO: 4 and has arabinofuranosidase (EC 3.2.1.55) activity, wherein the fragment has one or more amino acids deleted from the amino and/or carboxyl terminus of the mature polypeptide of SEQ ID NO: 4 and has at least 430 amino acids of the mature polypeptide of SEQ ID NO:
 4. 37. A method for producing a polypeptide having arabinofuranosidase activity, comprising cultivating the recombinant host cell of claim 31 under conditions conducive for production of the polypeptide, and recovering the polypeptide. 